1. Field of the Invention
The present invention relates to a cooling method and apparatus, and more particularly, to a cooling method and apparatus for a transformer, using a heat pipe.
2. Description of the Related Art
Electrical transformers are ubiquitous devices used for energy transfer and conversion. During operation, transformers heat up due to a plurality of factors. For example, current flowing through the transformer windings causes resistive heating of the transformer conductors, and consequently, heat dissipates from the conductors. Induced eddy currents may circulate within the core of the transformer, causing resistive heating. The heat produced by eddy currents in the core radiates out to other components of the transformer. Residual DC currents in the transformer also lead to transformer heating. Hence, transformer heating accompanies transformer operation. The amount of heat dissipated during transformer operation depends on the transformer size, weight, etc., and on the magnitude of voltages handled by the transformer.
Transformers typically have a large thermal resistance across their body. Due to large thermal resistances, conduction cooled transformers mounted on a cold plate often exhibit a large temperature delta across the distance from the cold plate to the hottest location on the transformer.
Disclosed embodiments of this application address these and other issues by utilizing a heat pipe supplemented cooling for a transformer. In accordance with the present invention, heat pipes are introduced in a transformer so that cooling is effectively applied to both sides (or multiple locations) of the transformer, thereby effectively reducing the thermal resistance across the transformer to the cold plate used to cool the transformer. This results in a cooler operating transformer, and/or a smaller and lighter transformer performing the same functions as larger transformers. According to one embodiment of the present invention, one or more heat pipes are embedded/introduced at various locations inside a conduction cooled transformer. Heat pipes efficiently move heat from transformer hotspots to a cold plate or other cold side of the transformer assembly. Heat pipes are evacuated devices that contain an amount of fluid. Heat dissipated from an operating transformer vaporizes fluid inside the heat pipes, and the formed vapors transport heat to regions of the heat pipes that are kept colder than the operating transformer.